The purpose of this project is to elucidate the mechanisms regulating estrogen production in primate pregnancy. The following two approaches are used: 1) determination of the factors controlling the availability of estrogen precursors in maternal and fetal compartments; 2) examination of the effects of variations in precursor availability on estrogen production. The studies provide an evaluation of the baboon as a model of human pregnancy. BIBLIOGRAPHIC REFERENCES: Schut, H.A.J. and Townsley, J.D.: Estrogen Formation from C19 Precursors in Human Choriocarcinoma in Culture. Acta Endocr. 84: 633-644, 1977. Townsley, J.D. and Pepe, G.J.: Serum Dehydroepiandrosterone and Dehydroepiandrosterone Sulfate in Baboon Pregnancy. Acta Endocr. 1977 (In Press).